Metallic particles have been incorporated in previously described compositions, typically for use as metal repair formulations, metallic paint finishes, and colorants.
Orsino, et al., disclosed a process of polymerizing olefinic materials directly onto metal particles and particle clusters using an organometallic-transition metal catalyst system, and to processes of making articles from the encased metal materials by molding, casting or extruding (U.S. Pat. No. 3,300,329). A variety of metals were so treated in the examples, including lead, boron, mercury, copper, gold, magnesium, aluminum, silicon, sponge iron, iron-silicon, nickel, manganese, and chromium. In example 14, a ferromagnetic plastic disc of iron with 10.3% polyethylene was made.
In U.S. Pat. No. 3,413,135, Matson prepared novel iron oxide pigments by contacting an aqueous presscake of hydrated feric oxide with a mixture of an aromatic mono-carboxylic acid such as benzoic acid and at least one higher fatty acid and working the mixture. A pigment was obtained upon separation and washing of the solid phase. Similarly, Tomkinson precipitated iron oxide with coloring matter to obtain pigments for bricks, plastics, textiles, and paints in U.S. Pat. No. 3,619,227. In one disclosed method, the coloring matter was formed in situ in an aqueous medium in which the precipitated iron oxide particles was suspended, and pigment was obtained from the suspension.
A corrosion-resistant primer or coating material containing stainless steel planar flakes of a rather critical geometry was disclosed by Novack in U.S. Pat. No. 3,954,482. The flakes, used only in certain proportions (about a pound per gallon primer), were 1/3.mu. in thickness and had a surface dimension of about 10.mu. to 40.mu.. The coating was disclosed as particularly efficacious as a one-coat anti-corrosive.
Okura, et al., also used plate-like particles in coating compositions for automobiles (U.S. Pat. No. 5,112,403). The particles were iron oxide, and had an average particle diameter of 0.5 to 5.0.mu., a lamillar thickness of 50 to 500 .ANG. and a plate ratio of 50:1 to 500:1. The composition further contained at least one pigment, a film-forming polymer, and an organic solvent.
In U.S. Pat. No. 4,129,528, McDonnell disclosed a two component system comprising a liquid polymerizable resin and a hardener, wherein one or both components contained a ferrosilicon alloy. On mixing the two components together, polymerization occurred, forming a composition useful as a metal repair or reclamation material.
Colloidal size particles such as an inorganic solid (titanium dioxide or magnetic iron oxide) encapsulated in a hydrophobic polymer such as a styrene polymer were disclosed in U.S. Pat. No. 4,421,660 to Hajna. They were disclosed as useful for a variety of applications, including separations, radiation absorption, magnetic paints, electrically resistive barriers, toners in electrophotographic applications, electroconductive additives for plastics, pigments in paint and ink formulations, and diagnostic materials. However, the process for preparing the matrix particulates was fairly complicated. It involved a polymerization wherein a hydrophobic monomer was dispersed in an aqueous colloidal dispersion of the inorganic particles that were preferably 0.005 to 0.1.mu. in size and then subjected to emulsion polymerization. The polymerizations generally employed free radicals; typical reactions involved heating with agitation under nitrogen and then adding a catalyst or free radical initiator. The matrix particulates so formed were separated from the aqueous continuous phase of the dispersion by conventional means such as drying.
Stratta and Stasiak dispersed ferromagnetic powder using a novel dispersing agent containing silylated alkylene oxide copolyethers or isocyanatoalkyl silanes in combination with phosphate esters for use in the manufacture of magnetic coatings for audio and video tape (U.S. Pat. No. 4,597,801). To achieve high information density storage on the tapes, the powders employed were of a very fine, high quality type that exhibited high coercive strength required by the electronics industry. For example, a cobalt-doped magnetic iron oxide particle size illustrated was 0.2.mu. in length; another that was not doped was 0.06.mu. by 0.35.mu. (column 11, lines 29 to 35).
In U.S. Pat. No. 4,834,800 to Semel, iron or steel powders were mixed with an alloying powder and a binding agent exhibiting certain properties. The agent was a film-forming resin insoluble in water comprising a vinyl acetate or methacrylate polymer, a cellulosic ester or ether resin, or an alkyd, polyurethane or polyester resin. The specific binding agents were disclosed as useful in enhancing the physical properties of the powder or sintered articles made from the powder. Where the binding agent was a substance that pyrolyzed relatively cleanly, residues of carbon or other chemicals were avoided during sintering of the composition.
Though many and varied, none of these patents disclose a magnetic paint or coating, or paint additive, that is simple to make and use, and inexpensive.